Xairflyer

My Feedback: (1)

Here we go again, this has to be the biggest deja Vu subject on RCU it pops up multiple times in multiple threads

Down thrust is always down thrust, the tailcone (exhaust) of the turbine may be pointing up but the thrust is pushing down, no matter if the turbine is at the front or back !

The way I get people to understand it is, thrust is a reaction force, so think on a rocket, the force out the back pushes it up (up thrust), which ever way the nose or front of the turbine (starter) is facing is the direction of thrust.

Rodh

Hi Alasdair, it is a Wren Supersport with a 2 litre coke bottle as a tank and Spring air retracts with a nose leg from Ali Machinsky as sold for the boomerang intro. Hope that helps
Rod

Aussie1

Mine also came out at 13lbs, with no fuel in the main tank. That includes 250gms of lead glued inside the rearmost part of the booms, at the bottom. Everything is mounted as far back as possible, and the tank is a 2.4 litre juice bottle which I never fill as it would fly all day! The engine is a PST600, which is actually lighter than my P60SE, and I have tried both engines on the airframe (not at the same time)! I did all the mods, including using 6mm thick marine ply plate as the mounts for the Dreamworks undercarriage. The U/C mounts in the kit will probaly last one flight if you fly it off grass, and don't modify it.

mk1spitfire

lol, how about this? What I meant is with turbine on the back its not like an engine on the front angled down, its angled up at the back!!

Yer aussie, 13lbs is great for you!! I think that other guy said his was 13lbs with supersport though.

Woketman

My Feedback: (6)

So? The top picture is down-thrust, and the bottom is up-thrust.

Xairflyer

My Feedback: (1)

In your drawings? the top one has down thrust and the bottom one is up thrust, unless the aeroplane is designed to go backwards

mk1spitfire

ha, I guess it gets confusing when you have a pusher and puller on a plane.!!!

BaldEagel

Thrust lines are relative to the Datum line drawn through the fus, the relative thust is a reaction so points in the direction it is pushing or pulling, therefore if the turbine being at the back is pointing up at the front, i.e. starter motor end it is up thrust.

When considering the need for up thrust on the Falcon we must consider the speed of the air under the tail having an effect, as we know the faster the air over or under an airfoil section compared to the relative airflow above or below will produce lift, in this case it has the opposite effect it pulls the tail down and therefore the nose up, this has to be compensated for either with up thrust or trimming of the tail incidence.

Mike

747junky

Has anybody heard of a new plane like the Falcon 120 that is going to be for sale soon? I over heard some people at the hobby shop talking about a plane that looks like the Falcon but is turbine ready with retracts and fuel tank for $475.00. I have been looking every were with no luck. If thats true it a hell of a lot cheaper with out the work. Please email me if anybody knows any info

Aussie1

Maybe this one? Based on the Falcon but with many improvements, including wing removal.

http://www.flyeaglejet.com/en/Trainer.html

And in relation to the definition of downthrust and upthrust, check out this discussion! I'm too chicken to buy into it!

http://www.rcgroups.com/forums/showthread.php?t=597244

BaldEagel

That is a rip of from Aviation Design, they did not even change the name: http://adjets.free.fr/ the Phoenix is the smaller version.

Mike

747junky

I will call the hobby shop and ask, but no its not fly eagle I think and besides fly eagle plane is over $1000 dollars. This plane there taking about is from the conversation I heard was $470 dollars complete with gear and composite fuel tank.

747junky

I just found out the story on that new jet I posted the info on the thread " New Jet Question andy info would help". Seems to be something to look for

Xairflyer

My Feedback: (1)

the fly eagle on in the blue camo looks good, funny how a colour scheme changes a model.

747junky

747junky

quote]ORIGINAL: Modellbau USA

Hello my name is Henry Castellanos, I am one of the new owners of Modellbau USA. We are releasing a new airplane called the Tornado. this airplane is a twin boom design that resembles the Bob Cat. We are not ready to post any pictures at the moment due to the expected release date being 2-3 months away. As stated in the previous posts, the airplane will come with Spring Air retracts and Composite fuel tank for around $475.00. We are currently flying one of the factory's prototypes in Florida. The kit is being made in our new factory in Ecuador. As soon as all the flight testing is complete we will begin pre-sales approximately November 15, 2010. If you have any further questions please feel free to email me at [email protected] or if you need spanish sales or assistance you may contact Alberto Enriquez at [email protected]
[/quote]


I guess it is true then.

joeflyer

My Feedback: (48)

Henry,

Will it also be available without the retracts?

Joe

Modellbau USA

My Feedback: (5)

The plane will be available with out the retracts by special order only, since they are being factory installed. We have partnered up with Spring Air Products to produce a custom set of retracts that are sold with the kit. Spring Air is making up a package of struts, wheels and brakes for this airplane that will be well under any thing that you can get on the market. What are goal with this project and our next jet (F86D) that we are expecting to release early next year is to give the consumer a good quality product with out having to break the bank. All of our kits will have composite fuel tanks, Spring Air retracts, and composite control horns. We will also be having special package deals with Jet Cat turbines

Xairflyer

My Feedback: (1)

Hats off to them for producing something at a realistic price and not doubling the price because it looks like a jet, look forward to seeing the F86

POWER JET

My Feedback: (3)

Hi ,

i've noticed, that all you guys,giving 3 to 6 degrees down thrust to turbine?.Why is that?I mean , you're doing this is for not to burn the elevator or for flight reasons?If i install  the turbine at 0 degrees is a mistake?

Thank's in advance for any replies....

fireblade5437

Hi

I have my 54 Wren angled down around 4deg, this is done so when you go full throttle the aircraft remains level. Having 0deg can cause the aircraft to climb when going to full throttle!

Alan

Xairflyer

My Feedback: (1)

deja who?

Yes it will help prevent the tail from getting hot/burnt, but it is not down thrust but up, the tail/rear of the turbine is angled down, which will also help it get off the ground better. Zero setting is still ok, but most find pointing the tail down a bit helps.

Xairflyer

My Feedback: (1)

If you have the rear of the turbine angled down and it stays level at full throttle then having it at 0deg will make it go down not up

Woketman

My Feedback: (6)

But that is not why it is there. The issue is that the high velocity turbine exhaust causes the air flowing under the horizontal stab to be faster than the air going over it. Bernoulli's effect then causes the stab to lift downwards, thereby creating a nose-up pitching moment that increases with turbine power. The exhaust down angle helps to alleviate this.

Woketman

My Feedback: (6)

Incorrect. Fireblade was correct, due to old man Bernoulli.